The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Debris suspended in the fluid circulating within a motor vehicle transmission is essentially without exception deleterious. Such material generally has two sources: the gears, shafts and other mechanical components within the transmission and the cast housing. While housings are generally alloys of aluminum or magnesium, the gears, shafts and other components are typically fabricated of ferrous alloys and are thus magnetic.
Hence, it is known and common in the prior art to include a strong permanent magnet within the transmission housing which attracts and collects ferrous particulates from the transmission fluid as it circulates within the transmission. The permanent magnet is often located in the sump where the transmission fluid collects and the least rapid and turbulent flow occurs.
While the incorporation of debris collecting permanent magnets in the sumps of motor vehicle transmissions has proven to be a practical and inexpensive solution to the fluid carried, ferrous debris problem, it is not without its shortcomings. Primary among these shortcomings is the lack of monitoring or oversight. Since the magnet is generally secured to the inside bottom of the transmission pan, it is virtually impossible to determine the quantity of material collected on any given magnet at any given time and thus (1) conclude that the magnet has served its useful life and must be either cleaned or replaced, (2) provide an estimate of the remaining magnet life as a debris collecting component or (3) provide any assessment of debris related problems, without dropping the transmission pan and inspecting the magnet.
At the very least, dropping the transmission pan involves removing and re-installing a large plurality of machine bolts and providing a new gasket. Clearly, therefore, this step in not undertaken without some reason, such as replacement of the filter and transmission fluid or service to the internal components of the transmission. During such maintenance, of course, the debris collecting magnet can be either cleaned or replaced but such maintenance is today typically separated by long service intervals. From the foregoing, it is apparent that a means or method of monitoring the accumulation of debris on a permanent magnet debris collector of a motor vehicle transmission would be both desirable and useful.